1. Field of the Invention
This invention is related to the composition and method for detection of cationic polymers in aqueous systems.
2. Description of Related Art
Cationic polymers are widely used in industrial aqueous systems and wastewater treatment process, drinking water treatment process, such as polydiallyldimethylammonium chloride (polyDADMAC), cationic acrylamide copolymers, epichlorohydrin-dimethylamine polymers, and polyethyleneimine. However, the residual cationic polymer is always a concern in some aqueous systems, such as waste water treatment process, drinking water treatment process, food process, membrane treatment process and so on. At the same time, regulations become more rigorous regarding the presence of residual cationic polymers in treated water. Therefore the ability to track the residual polymer concentration in aqueous system is highly desirable to increase in efficiency of the chemical treatment program, allow for diagnostic troubleshooting, and insure to meet regulatory control of residual polymer discharge.
Currently, there are several common types of water-soluble polymer detection methods: (1) settling rate of clay suspensions; (2) size-exclusion chromatograph with ultraviolet detection; (3) turbidmetry of complexes between oppositely charged polymers; (4) fluorescent tagging; (5) colorimetry; and (6) immunoassay method.
Immunoassay techniques are used to determine the presence or concentration of a water treatment polymer in an aqueous system as described in U.S. Pat. No. 6,911,534B2; U.S. Pat. No. 6,420,530; U.S. Pat. No. 6,197,522B1; and U.S. Pat. No. 5,593,850. Monoclonal or polyclonal antibodies to different water treatment polymers are prepared and the antibody is applied as a reagent in an immunoassay on the target aqueous samples. It was reported that immunoassay detection technology was already in existence for coagulant polymers epichlorohydrin-dimethylamine and polydiallyldiammonium chloride and cationic copolymer or terpolymer, which contained monomer of diallyldimethylammonium chloride.
Another approach to detect the polymers is fluorescent tagging techniques, wherein a fluorescent group is introduced to the target polymer molecular structure, either during or after the polymerization, and then utilized for fluorescence monitoring as described in U.S. Pat. Nos. 4,813,973; 5,171,450; 5,705,394; and 6,312,644. With this approach the polymer is positively indicated by florescence. But many aqueous systems wherein the polymers are utilized often contain other sources of fluorescence, therefore, application of fluorescent marker may be impractical, as it becomes difficult to reliably distinguish low levels of fluorescence arising from aqueous systems. Furthermore luminol derived monomer was developed as described in U.S. Pat. No. 6,077,461. The chemiluminescent groups were also introduced to polymer molecule, the chemiluminescent group could be detected with a very low level limit, even in systems containing impurities which either quench fluorescence or fluoresce themselves.
However, the above detection methods generally either have poor sensitivities, which require a preconcentration step, or require the introduction of other functional groups before the polymer structure can be tested. Additionally, these methods often introduce secondary contamination into the tested solution, such as fluorescent groups or non-environmentally friendly dyes, which require extra waste treatment before disposal. Also, these methods require the use of expensive fluorescent monomer, dye and antibodies.
Thus, there exists a strong need for a simplified test method that can easily be used to determine the concentration of cationic polymers in aqueous systems.